Chin J Plant Ecol ›› 2011, Vol. 35 ›› Issue (1): 35-44.DOI: 10.3724/SP.J.1258.2011.00035

• Research Articles • Previous Articles     Next Articles

Seed rain, soil seed bank and seedling regeneration in a 65-year Picea asperata plantation in subalpine coniferous, western Sichuan, China

YIN Hua-Jun1,2, CHENG Xin-Ying1,2, LAI Ting1, LIN Bo1,2, LIU Qing1,2,*()   

  1. 1Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
    2Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Chinese Academy of Sciences, Chengdu 610041, China
  • Received:2010-04-14 Accepted:2010-06-03 Online:2011-04-14 Published:2011-01-24
  • Contact: LIU Qing

Abstract:

Aims Picea asperata is one of the keystone spruce species used for reforestation in subalpine coniferous forest of western Sichuan, China. A total of ca. 13 000 hm2 of plantations are dominated by this species in this region. Our objective was to assess (a) potential for natural regeneration and (b) critical factors limiting regeneration of this tree species in spruce plantations.
Methods We conducted field studies on the seed rain, soil seed bank dynamics and seedling establishment in a 65-year spruce plantation in Miyaluo subalpine coniferous forest of western Sichuan, China from 2002 to 2008. We used seed traps, sieved to determine the soil seed bank, and recorded seedlings.
Important findings Pinus asperata seed rain commonly lasted from early October to the end of January or early February. There was a large annual variation in seed production, with mast years at 4-year intervals. We concluded that seed availability was not a limiting factor for natural regeneration, at least in mast years. The seed bank was transient, with losses from seed decay and seed predation being the two most important factors affecting seed bank dynamics. Only a small fraction of seeds germinated and produced seedlings, e.g., 3.6% in 2002. Higher seedling mortality greatly reduced the total number of germinated seedlings, and few seedlings survived after one growing season. Deep litter and moss were the most common substrates for P. asperata regeneration, having 93% of all germinated seedlings. Most surviving seedlings occurred with a substrate depth of 0-2 cm, and seedling mortality increased with greater depth, suggesting substrate depth is an important constraint on natural regeneration. Seedlings on moss substrate had greater root collar diameter, number of green shoots, estimated dry weight and annual dry weight increment but less height than those on litter substrate. In conclusion, despite a substantial seed production, high depletion of soil seed, low germination and high seedling mortality limit natural regeneration of P. asperata.

Key words: Picea asperata, plantation, regeneration, seed rain, soil seed bank, subalpine coniferous forest